U.S. patent application number 13/001896 was filed with the patent office on 2011-05-12 for reversible permeability measuring device.
This patent application is currently assigned to KOREA RESEARCH INSTITUTE OF STANDARDS AND SCIENCE. Invention is credited to In Hyun Cheong, Jong Seo Park, Soo Young Park, Kwon Sang Ryu, Kee-Bong Yoon.
Application Number | 20110112789 13/001896 |
Document ID | / |
Family ID | 41466462 |
Filed Date | 2011-05-12 |
United States Patent
Application |
20110112789 |
Kind Code |
A1 |
Ryu; Kwon Sang ; et
al. |
May 12, 2011 |
Reversible Permeability Measuring Device
Abstract
The present invention relates to a reversible permeability
measuring device for measuring magnetic characteristics and
magnetic flux change in a specimen, as one of a plurality of
non-destructive methods for evaluating mechanical properties. The
reversible permeability measuring device of the present invention
directly measures a magnetic field change induced at the surface of
the specimen through the use of a magnetic potentiometer and a flux
meter, thereby accurately evaluating the deterioration of
materials.
Inventors: |
Ryu; Kwon Sang; (Daejeon,
KR) ; Park; Soo Young; (Daejeon, KR) ; Park;
Jong Seo; (Daejeon, KR) ; Cheong; In Hyun;
(Daejeon, KR) ; Yoon; Kee-Bong; (Yongin-si,
KR) |
Assignee: |
KOREA RESEARCH INSTITUTE OF
STANDARDS AND SCIENCE
Daejeon
KR
Chung-Ang Univerisity Industry-Academy Cooperation
Foundation
Seoul
KR
|
Family ID: |
41466462 |
Appl. No.: |
13/001896 |
Filed: |
July 1, 2009 |
PCT Filed: |
July 1, 2009 |
PCT NO: |
PCT/KR2009/003573 |
371 Date: |
December 29, 2010 |
Current U.S.
Class: |
702/115 |
Current CPC
Class: |
G01R 33/1223
20130101 |
Class at
Publication: |
702/115 |
International
Class: |
G06F 19/00 20110101
G06F019/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 2, 2008 |
KR |
10-2008-0063810 |
Claims
1. A reversible permeability measuring device, comprising: a
surface type probe including a DC driving coil wound to an
outermost side and applying DC magnetic field, an AC driving coil
wound to the inner side of the DC driving coil and applying AC
perturbing magnetic field to the applied DC magnetic field, a pick
up coil wound to the inner side of the AC driving coil and picking
up the induced AC perturbing magnetic field, and a yoke wound with
the coils and spacing a specimen from the coils; a magnetic
potentiometer provided in the inner side of the surface type probe
and detecting magnetic field induced from the surface of the
specimen; an AC function generator applying an AC magnetic field
function to the AC driving coil; a lock-in amplifier measuring
reversible permeability induced to the pick up coil by using the
frequency of the applied AC perturbing magnetic field as a
reference signal; a fluxmeter measuring the magnetic field induced
from the surface of the specimen, which is detected from the
magnetic potentiometer; an I/O acquisition board applying a DC
magnetic field function to the DC driving coil, applying the AC
magnetic field to the AC driving coil, and being applied with the
magnetic field induced from the surface of the specimen measured in
the fluxmeter; a power amplifier applying power in a function
applied from the I/O acquisition board 60 to the DC driving coil;
and a microcomputer directly calculating the reversible
permeability induced to the pick up coil input to the I/O
acquisition board and the magnetic field generated from the surface
of the specimen measured in the fluxmeter.
2. The reversible permeability measuring device of claim 1, wherein
the magnetic potentiometer is provided in the inner side of the
yoke.
Description
TECHNICAL FIELD
[0001] The present invention relates to a reversible permeability
measuring device, and more particularly, to a reversible
permeability measuring device for measuring magnetic
characteristics and magnetic flux change in a specimen, as one of a
plurality of non-destructive methods for evaluating mechanical
properties.
BACKGROUND ART
[0002] Since mechanical properties of structural steel, turbine
rotor steel, or the like, are associated with magnetic
characteristics, the mechanical properties are evaluated by
non-destructively measuring magnetic characteristics.
[0003] A coil used for a magnetic characteristic measuring device
for measuring the magnetic characteristics is largely classified
into a surface type probe measuring the change in a magnetic flux
generated from a specimen by vertically disposing a coil on a
surface of a specimen to be measured and an encircling type probe
winding a coil around a round bar or a flake type specimen The
former is used to measure Barkhausen noise (BN) or harmonics and
the latter is used to measure a magnetic hysteresis curve in
addition to the BN or the harmonics. Among others, the former is
usefully used for the magnetic evaluation of a non-destructively
operated material.
[0004] An example of the reversible permeability measuring device
was disclosed in paper "Nondestructive evaluation of aged
1Cr-1Mo-0.25V steel by harmonic analysis of induced voltage" (JMMM,
Volume 231, 2001. 3) published in Journal of Magnetism and Magnetic
Materials by the inventors.
[0005] The paper defines the correlation capable of measuring
Vickers hardness, yield strength, and tensile strength, all of
which are mechanical properties of artificially deteriorated
1Cr-1Mo-0.225V steel, non-destructively measuring reversible
permeability that is a primary harmonic of an AC magnetic field
with the surface type probe, and inferring mechanical properties
with a coercive force that is 1/2 of a peak interval of reversible
magnetic permeability.
[0006] A system of measuring reversible permeability with the
surface type probe used in the paper was shown in FIG. 1.
[0007] The surface type probe is manufactured by winding a pick up
coil to a yoke and then, winding an AC driving coil and a DC
driving coil thereto. Meanwhile, a direct current is applied by
power-amplifying a function generated from an I/O acquisition board
with a power amplifier and an AC magnetic field applies a function
generated from a function generator. The reversible permeability
induced to the pick up coil is measured by a lock-in amplifier
using a frequency of the AC magnetic field as a reference signal
and values read by a shunt and the lock-in amplifier are measured
through an input side of the I/O acquisition board and are then
processed as data in a computer.
[0008] The magnetic characteristic measuring device having the
above-mentioned structure uses a manner that obtains current from
the voltage measured in the shunt to indirectly calculate a
magnetic field H through the following Equation 1.
H = ni 1 Equation 1 ##EQU00001##
[0009] (n: winding number per unit length, i: current obtained in
shunt, and 1: average magnetic path)
[0010] As represented by Equation 1, when the magnetic field H is
calculated, it is calculated by an indirect calculation scheme,
such that the measured value of the reversible permeability is
inaccurate and the reliability of deterioration evaluation on
materials is degraded.
[0011] The correlation capable of inferring the mechanical
properties with a coercive force that is 1/2 of a peak interval of
reversible magnetic permeability (PIRMP) using the magnetic
characteristic measuring device having the above-mentioned
structure is obtained, as shown in FIG. 2.
[0012] In this case, the measurement of the coercive force that is
1/2 of the peak interval of reversible magnetic permeability
(PIRMP) is made as shown in a graph of FIG. 2. However, the graph
shows result values that do not form a symmetry, such that the
mechanical properties cannot be inferred accurately.
DISCLOSURE
Technical Problem
[0013] An object of the present invention is to provide a
reversible permeability measuring device capable of more accurately
evaluating deterioration of a material by directly measuring
magnetic field on a surface of a specimen.
Technical Solution
[0014] In one general aspect, a reversible permeability measuring
device includes: a surface type probe 10 including a DC driving
coil 11 wound to an outermost side and applying DC magnetic field,
an AC driving coil 12 wound to the inner side of the DC driving
coil 11 and applying AC perturbing magnetic field to the applied DC
magnetic field, a pick up coil 13 wound to the inner side of the AC
driving coil 12 and picking up the induced AC perturbing magnetic
field, and a yoke 14 to which the coils 11, 12, and 13 are wound
and spacing a specimen 1 from the coils 11, 12, and 13; a magnetic
potentiometer 20 provided in the inner side of the surface type
probe 10 and detecting magnetic field induced from the surface of
the specimen 1; an AC function generator 30 applying an AC magnetic
field function to the AC driving coil 12; a lock-in amplifier 40
measuring reversible permeability induced to the pick up coil 13 by
using the frequency of the applied AC perturbing magnetic field as
a reference signal; a fluxmeter 50 measuring the magnetic field
induced from the surface of the specimen 1, which is detected from
the magnetic potentiometer 20; an I/O acquisition board 60 applying
a DC magnetic field function to the DC driving coil 11, applying
the AC magnetic field to the AC driving coil 12, and being applied
with the magnetic field induced from the surface of the specimen
measured in the fluxmeter 50; a power amplifier 70 applying power
in a function applied from the I/O acquisition board 60 to the DC
driving coil 11; and a microcomputer 80 directly calculating the
reversible permeability induced to the pick up coil 13 input to the
I/O acquisition board 60 and the magnetic field generated from the
surface of the specimen 1 measured in the fluxmeter 50.
[0015] The magnetic potentiometer 20 may be provided in the inner
side of the yoke 14.
Advantageous Effects
[0016] The present invention improves the problem in that the
measured value of the magnetic field is inaccurate and the
reliability of deterioration evaluation on materials is degraded,
due to the magnetic field H calculated by the indirect calculation
manner. That is, the present invention directly measures the
magnetic field generated on the surface of the specimen by using
the magnetic potentiometer and the fluxmeter, thereby making it
possible to more accurately evaluate the deterioration of the
material.
DESCRIPTION OF DRAWINGS
[0017] The above and other objects, features and advantages of the
present invention will become apparent from the following
description of preferred embodiments given in conjunction with the
accompanying drawings, in which:
[0018] FIG. 1 is a diagram showing a reversible permeability
measuring device according to the related art;
[0019] FIG. 2 is a graph measuring reversible permeability using
the reversible permeability measuring device according to the
related art;
[0020] FIG. 3 is a diagram showing a reversible permeability
measuring device according to the present invention; and
[0021] FIG. 4 is a graph measuring reversible permeability using
the reversible permeability measuring device according to the
present invention.
DETAILED DESCRIPTION OF MAIN ELEMENTS
[0022] 1: SPECIMEN 10: SURFACE TYPE PROBE [0023] 11: DC DRIVING
COIL 12: AC DRIVING COIL [0024] 13: PICK UP COIL 14: YOKE [0025]
20: MAGNETIC POTENTIOMETER 30: AC WAVEFORM GENERATOR [0026] 40:
LOCK-IN AMPLIFIER 50: FLUXMETER [0027] 60: I/O ACQUISITION BOARD
70: POWER AMPLIFIER [0028] 80: MICROCOMPUTER.
BEST MODE
[0029] Hereinafter, a reversible permeability measuring device
according to the present invention will be described with reference
to the accompanying drawings.
[0030] FIG. 3 is a diagram showing a reversible permeability
measuring device according to the present invention and FIG. 4 is a
graph measuring the reversible permeability using the reversible
permeability measuring device according to the present
invention.
[0031] As shown, the reversible permeability measuring device
according to the present invention is configured to include a
surface type probe 10 including a DC driving coil 11, an AC driving
coil 12, a pick up coil 13, and a yoke 14 wound with the coils 11,
12, and 13; a magnetic potentiometer 20 detecting magnetic field
induced from the surface of the specimen 1; an AC function
generator 30 applying an AC magnetic field function to the AC
driving coil 12; a lock-in amplifier 40 measuring reversible
permeability of a specimen induced to the AC driving coil 12; a
fluxmeter 50 measuring the magnetic field induced from the surface
of the specimen 1; an I/O acquisition board 60 applying the
reversible permeability of the specimen induced to the AC driving
coil 12 and being applied with the magnetic field induced from the
surface of the specimen 1 measured in the fluxmeter 50; a power
amplifier 70 applying power to the DC driving coil 11; and a
microcomputer 80 directly calculating the reversible permeability
of the specimen induced to the pick up coil 13 and the magnetic
field induced from the surface of the specimen 1 measured in the
fluxmeter 50.
[0032] The surface type probe 10 is configured to include the DC
driving coil 11, the AC driving coil 12, the pick up coil 13, and
the yoke 14 wound with the coils 11, 12, and 13, wherein the pick
up coil 13, the AC driving coil 12, and the DC driving coil 11 are
sequentially wound from the inner side of the yoke 14.
[0033] The DC driving coil 11 is wound to the outermost side of the
yoke 14 and applies the DC magnetic field. In this case, the
applied DC magnetic field is applied through the power amplifier 70
in the DC magnetic field function applied from the I/O acquisition
board.
[0034] The AC driving coil 12 is wound to the inner side of the DC
driving coil 11 and serves to induce the AC perturbing magnetic
field to the applied DC magnetic field.
[0035] The pick up coil 13 is wound to the inner side of the AC
driving coil 12 and detects the DC magnetic field and the
reversible permeability of the specimen induced by the AC
perturbing magnetic field by the lock-in amplifier 40 using the
frequency of the AC perturbing magnetic field as the reference
signal.
[0036] The yoke 14 is wound with the coils 11, 12, and 13 and
spaces the specimen 1 from the coils 11, 12, and 13.
[0037] The magnetic potentiometer 20 is provided in the inner side
of the surface type probe 10 and serves to detect the magnetic
field induced from the surface of the specimen 1. In this case, the
magnetic potentiometer 20 may be provided in the inner side of the
yoke 14.
[0038] The function generator 30 serves to apply the AC magnetic
field function to the AC driving coil 12. The DC magnetic field
applied from the DC driving coil 11 applies the AC magnetic field
from the AC function generator 30 to induce the AC perturbing
magnetic field.
[0039] The lock-in amplifier serves to measure the reversible
permeability of the specimen induced to the pick up coil 13 using
the frequency of the AC magnetic field function as the reference
signal.
[0040] The fluxmeter 50 serves to directly measure the magnetic
field induced from the surface of the specimen 1 detected from the
magnetic potentiometer 20. Therefore, when the magnetic field H
generated from the surface of the specimen is calculated, the
related art calculates the magnetic field generated from the
surface of the specimen through the indirect calculation manner
rather than through the direct calculation manner, while the
present invention directly measures the magnetic field generated
from the surface of the specimen, thereby making it possible to
obtain the accurate measured values and improve the reliability of
deterioration evaluation on materials.
[0041] The I/O acquisition board 60 applies the DC magnetic field
function to the DC driving coil 11 and applies the reversible
permeability induced to the pick up coil 13 and the reversible
permeability induced from the surface of the specimen 1 measured in
the fluxmeter 50.
[0042] The power amplifier 70 serves to apply power in the function
applied from the I/O acquisition board 60 to the DC driving coil
11.
[0043] The microcomputer 80 directly calculates the reversible
permeability induced to the pick up coil 13, which is input to the
I/O acquisition board 60, and the magnetic field induced from the
surface of the specimen 1 measured in the fluxmeter 50.
[0044] FIG. 4 is a graph measuring the reversible permeability
using the reversible permeability measuring device according to the
present invention, wherein the reversible permeability of the
specimen is measured according to the change in DC magnetic
field.
[0045] As shown, it can be appreciated that the graph has result
values of the left and right symmetrical structure. As such, as the
graph has the left and right symmetrical structure, the coercive
force that is 1/2 of the peak interval of reversible magnetic
permeability (PIRMP) can be more accurately measured and the
mechanical properties can be more accurately inferred.
INDUSTRIAL APPLICABILILTY
[0046] The present invention improves the problem in that the
measured value of the magnetic field is inaccurate and the
reliability of deterioration evaluation on materials is degraded,
due to the magnetic field H calculated by the indirect calculation
manner. That is, the present invention directly measures the
magnetic field generated on the surface of the specimen by using
the magnetic potentiometer and the fluxmeter, thereby making it
possible to more accurately evaluate the deterioration of the
material.
* * * * *